1. Field of the Invention
The present invention relates to a pattern recognition system, and more specifically to a general pattern recognition system capable of recognizing a given pattern in an analog manner without regard to the size and the direction of the whole of the given pattern.
2. Description of Relates Art
At present, so-called pattern recognition systems are widely used in an industrial field, for example as apparatuses for reading letters and systems for sorting components or parts. The feature of recognition method common to the conventional systems is to firstly extract various characteristics, which are commonly contained in a group of objects to be recognized, from the input pattern data, and then to categorize on the basis of the extracted characteristics.
The processing part of such recognition systems comprises a digital processor and a special circuit which quantitatively extracts specific characteristics, such as a high speed Fourier transformation circuit. The program for the digital processor can be designed according to the objects for recognition. Such a recognition system is specialized to meet the very first industrial demand for a high-speed recognition.
On the other hand, the specialization of the recognition system makes it necessary to design an system and a program for each recognition object category. As a result, the related techniques are more specialized, and design and modification works have become more complicated. Furthermore, the complication of category classification processing lowers the reliability of recognition results, resulting in more difficult quality control of products manufactured in the production system using the pattern recognition system.
On the viewpoint of tho manufacture's side, this follows that a high degree of design work is required for each of specifications of orders received, and that the cost of product including training of engineers becomes higher.
On the viewpoint of the user's side, there exist disadvantages on the technical point and the cost in use such that the technical information on the recognition objects themselves which are wanted to be held only at the user can flow out to the maker's side, and such that the user is forced to frequently change the system to a new model with improved function.
As above-described, the pattern recognition system has encountered with disadvantages of the specialization and complication.
In this situation, general purpose pattern recognition systems have been proposed in Japanese Patent Application Laid-open Nos. SHO 61-127,075 and SHO 61-127,076 and U.S. Pat. No. 4,710,964, which systems are capable of recognizing a given pattern in an analog manner without regard to the size and the direction of the whole of the given pattern.
These pattern recognition systems are such that the dependency of the construction of the softwares and the hardwares upon the kinds of objects to be recognized has been greatly decreased. Therefore, it has become possible for the maker to mass-manufacture a small kinds of systems, which would enable decrease of the cost and the increase of the reliability. On the other hand, the user can accumulate data concerning the pattern of objects to be recognized, indepandently of an outside such as the maker. In other words, these pattern recognition systems have succeeded in achieving the objects of the inventions. However, the these recognition systems could not still be satisfied, because these systems cannot discriminate patterns composed of two diagonal line segments such as a cross or plus-sign pattern, a L-shaped pattern and a T-shaped pattern, and a pair of parallel line segments adjacent to each other.
Further, the above mentioned pattern recognition system cannot discriminate a graphic pattern composed of a closed line, such as a triangle and a rectangle.